The reactions of fluoroalkanesulfonyl azides 1 with some electron-rich olefins have been studied. Alkyl vinyl ethers reacted with 1 readily at 0 degreesC or room temperature (RT) and did not give the corresponding N-fluoroalkanesulfonyl azilidines but 1-fluoroalkanesulfonyl-1,2,3-triazolines 3, which decomposed slowly at room temperature to form 1,4-fluoroalkanesulfonyl-2,5-alkoxyl-piperazines 4 with elimination of nitrogen gas. In contrast, more electron-rich alkene, tetrakis(dimethylamino)ethylene (TDAE) reacted with 1 affording N-fluoroalkanesulfonyl bis(dimethylamino)amidines 6 accompanying the release of N-2. Reaction mechanisms are discussed. (C) 2003 Elsevier B.V. All rights reserved.